In recent years, information provision technologies via communication networks have been evolving considerably through a series of technologies called Web technology. In information provision with the Web technology, a digitalized content is delivered via a communication network in a format called HTML (Hyper Text Markup Language), and software called a Web browser displays the content to users, and receives user manipulations. The Web browser mainly performs operations as described below.
1. The Web browser converts HTML data into tree-structure data called a DOM (Document Object Model) format.
2. The Web browser displays the data on the screen by applying display designs to elements in the DOM based on CSS (Cascading Style Sheets) data.
3. With a script language called JavaScript (Registered Trademark) (which is also called ECMAscript), the Web browser interacts with users or makes a dynamic change to the screen, by dynamically performing DOM operations (element generation/deletion/movement, attribute setting/reference, property setting/reference, method call, and the like) in an initial display and on the occurrence of various types of events (pointer manipulation, keyboard entry, and clicking on elements on the DOM such as a button and the like which are performed by users, timer, reception of asynchronous communications, and the like).
As described above, HTML data, JavaScript codes and CSS data integrally to constitute digital content data.
The Web technology has been implemented very often as the information provision technology, and libraries or tools for facilitating use of the Web technology are widely known. For example, use of the library released as JQuery enables simple implementation of JavaScript for executing DOM operation processes or performing setting of processes on events.
In addition, technologies for delivering a digital content to a plurality of devices through the use of the Web technology have been developed. For example, Non-Patent Document 1 discloses a technique by which in conjunction with a video content displayed on a television receiver, a related content is displayed on a tablet terminal by operating Web browsers on the television receiver and the tablet terminal. The technique of operating the Web browsers cooperatively is described with reference to FIG. 34. HTML data including video elements for playing motion video is delivered to a Web browser 100A operating on a television receiver, while HTML data including elements for displaying related information is delivered to a Web browser 100B operating on a tablet terminal. JavaScript for communicating necessary information via a WebSocket server 200 is prepared in the HTML data to be delivered to the Web browsers 100A, 100B. The Web browser 100A transmits to the WebSocket server 200 metadata which is embedded in motion video in accordance with motion video to be played. The WebSocket server 200 transmits to the Web browser B information related to the received metadata. Then, the information related to the motion video to be played is displayed on the Web browser 100B.